Fascinating images showing three portions of the same meal reveal the exact amount of food you need to eat to lose, maintain or GAIN weight (and the difference between them is huge)

The first rules of dieting are to give up unhealthy treats and to eat less.

But a study by the British Medical Journal has revealed that most people rely on their sight to control portion sizes – which can result in them consuming an extra 300 calories a day.

Now a new series of images reveals the exact amount of food you should eat to lose, maintain or gain weight by showing three different sized portions of the same meal – and the difference in size between the smallest and largest portions is huge.

A new series of images, such as this one of a chicken and courgetti salad, reveals exactly how much you should eat to lose weight (top); maintain your weight (bottom left) and gain weight if you want to bulk up (bottom right)

This image reveals how much of a chicken salad sandwich you should eat if you want to: lose weight (top); maintain weight (bottom left); or gain weight (bottom right)

The series of images show three meals laid out on a table, which all have different portion sizes.

The smallest reveals the exact amount of food needed to lose weight, the central plate is the amount needed to maintain weight and the largest plate is the amount needed to gain weight.

Gaining weight may be the last thing on some people’s minds but many fitness fans want to bulk up or increase muscle mass.

The images – created by the makers of kitchen gadget MealKitt, a portion control box developed by a personal trainer – are all of healthy meals that fitness fanatics are advised to eat if they want to slim down, maintain their weight or to bulk up.

How much avocado toast with salmon should you be eating? It depends if you want to: lose weight (left), maintain weight (centre), or gain weight (right)

The number of roasted vegetables in this rice and veg dish (left) increases if you want to lose weight (top), maintain weight (bottom left), or gain weight (bottom right). With a salmon, tomatoes and grains dish (right), the amount of grains and salmon fillet also increases depending on losing (top), maintaining (bottom left), or gaining weight (bottom right)

How much parsnip soup with bread you should eat depending on whether you want to lose weight (left), maintain weight (centre), or gain weight (right)

Portion sizes for losing, maintaining and gaining weight

Experts say:

LOSING WEIGHT

Meals should be made up of 45 per cent protein, 35 per cent fat, and 20 per cent carbohydrates. Women need to eat 1,400 calories a day and men need to eat 1,900.

MAINTAINING WEIGHT

Meals should be made up of 35 per cent protein, 30 per cent fat, and 40 per cent carbohydrates. Women should eat 2,000 calories a day, and men 2,500.

GAINING WEIGHT

Meals should be made up of 30 per cent protein, 20 per cent fat, and 50 per cent carbohydrates. Women should eat 2,600 calories a day, and men 3,100 a day.

With this rice and ratatouille dish, the amount of vegetables decreases and the amount of rice increases between the lose weight portion (left), maintain weight portion (centre) and the gain weight portion (right)

This image (left) reveals the amount of quiche and salad you need to eat to lose weight (top), maintain weight (bottom left), and gain weight (bottom right). Similarly, the top bowl of porridge (right) is the amount needed to gain weight, the bowl on the left for maintaining and the bowl on the right for losing weight

This image reveals how much of a beetroot and potato salad you should eat to lose weight (left), maintain weight (centre) and gain weight (right)

Like scrambled eggs? This is how much you should eat to lose weight (left), maintain weight (centre), and gain weight (right)

This image reveals how much mushrooms on toast you should eat if you want to lose weight (left), maintain weight (centre) and gain weight (right)

This snap reveals how much prawn and vegetables and rice you should eat if you want to lose weight (left), maintain weight (centre) and gain weight (right)

The number of sandwiches you should eat depends if you want to lose weight (bottom right), maintain weight (left), or gain weight (top)